For shipping and storage, many types of fibrous material can be pressed and bound into bales. Such bales usually have a particular size and shape, depending upon the type and characteristics of the material in the bale and the type of baling machine used. Substantially uniform bales, particularly those having square or rectangular profiles, are advantageous because they usually require no packaging material other than wire, twine, or strapping to hold the bale together and because they can be tightly stacked with minimal space between bales.
A bale of fibrous material may be of relatively low density for any of various reasons. First, the material may contain moisture; a dense bale may not allow material in the interior of the bale to aerate properly, which may cause rotting. Second, an overly dense bale may damage the fibers, especially if they are not oriented properly relative to the compression and binding. Third, dense bales may be too heavy for a person to handle without equipment. Fourth, some materials may be extremely resistant to compaction, resulting in recoil forces on the bindings that exceed the strength of the binding materials. Fifth, material compressed too tightly may become too difficult to separate later when the bale is opened.
However, it is often desirable to bale fibrous material in the densest bale practicable because storage and shipping costs based on volume rather than weight will be lower with denser bales. If the particular material will permit, recompressing low-density bales into high-density bales especially for long-distance shipping may appreciably lower shipping costs, which will make the product more price-competitive in its destination market.
Mown and dried herbaceous forage for livestock is commonly baled for shipping and storage. Hay (alfalfa, timothy, grass, clover, etc.) and straw (stalks of wheat, oats, grass, etc.) are customarily bound in the field into several different types and sizes of bale, in both cylindrical (round bales) and rectangular solid shapes (“rectangular” and “square” bales) having a density of approximately six to ten pounds per cubic foot or less.
Unfortunately, compressing such forage to higher densities than the common density six to ten pounds per cubic foot can damage the plant structure and reduce the value of the compacted forage. Thus, what is needed is a method for compacting forage to greater densities that is capable of preserving the plant structure from shattering while retaining the value of the double compressed forage.